title: Summary measures of adherence using pill counts in two HIV prevention trials: the need for standardisation in reporting.
abstract: For trials of user-dependent HIV prevention products, accurate adherence measurements are essential to interpret and compare results across trials. We used pill count data from two recent HIV prevention trials of herpes simplex virus type 2 (HSV-2) suppression, to show that estimates of adherence vary substantially depending on assumptions that are made in analysing pill count data. We associate calculated adherence with biological markers of anti-HSV-2 activity. In both trials, calculated adherence varied considerably, depending on the summary measure used, and the handling of intervals with apparent 'over-adherence' (fewer pills returned than expected), and unreturned pills. Intervals of apparent over-adherence were associated with reduced antiviral effects on biological markers of herpes reactivation, indicating these are likely to represent periods of non-adherence. Our results demonstrate the clear need for standardisation in reporting of adherence data that are based on pill counts.
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK, kathy.baisley@lshtm.ac.uk.
authors.forename: Kathy
authors.initials: K
authors.lastname: Baisley
authors.forename: Jared M
authors.initials: JM
authors.lastname: Baeten
authors.forename: James P
authors.initials: JP
authors.lastname: Hughes
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Donnell
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Richard
authors.initials: R
authors.lastname: Hayes
authors.forename: Deborah
authors.initials: D
authors.lastname: Watson Jones
authors.forename: Connie
authors.initials: C
authors.lastname: Celum
mesh_terms: D000212:Acyclovir / Q000008:administration & dosage*; D000328:Adult; D000349:Africa / Q000453:epidemiology; D000998:Antiviral Agents / Q000008:administration & dosage*; D018791:CD4 Lymphocyte Count; D004311:Double-Blind Method; D005260:Female; D015658:HIV Infections / Q000453:epidemiology / Q000517:prevention & control*; D006558:Herpes Genitalis / Q000188:drug therapy* / Q000453:epidemiology; D006801:Humans; D008297:Male; D008499:Medical Records / Q000592:standards*; D010568:Peru / Q000453:epidemiology; D036301:Qualitative Research; D012646:Self Administration; D014481:United States / Q000453:epidemiology; D019562:Viral Load; D016903:Drug Monitoring
chemical_list: D000998:Antiviral Agents; D000212:Acyclovir